The Assignee has observed that it is becoming desirable in many applications to use modular memory units which are easily removed.
Magnetic memory cassettes have this property. However the access time to information stored thereon is prohibitive.
Other magnetic memories such as floppy disks or removable hard disks are no better, since although their access time is better, they require certain precautions to be taken in use and storage which makes them unusable in practice.
There are also electronic memories, i.e. memories in which input/output to the physical memory element takes place by way of electrical signals. Devices of this nature exist; however they do not provide a large memory capacity nor do they provide the high degree of security required in some of the applications in which the Assignee is interested, such as aviation.
In particular, rather than increasing the capacity of the central memory of onboard computers, the Applicant considers it to be preferable to use modular mass memories which can be used both on the ground and in an aircraft, and which are capable of being loaded via a bus.
The basic problem is thus to provide modular mass memories having a capacity of at least one megabit and which are greatly extensible. This problem is complicated by the fact that such memories must be highly reliable, compact, and must above all continue to perform well under extreme environmental conditions, e.g. -55.degree. C. to +125.degree. C. temperature range while being subjected to a high level of vibration.
Preferred implementations of the present invention provide a solution to this problem.